Semiconductor device and method

Abstract

In some embodiments, laser devices having contact pads are formed. The laser diodes are formed from a doped semiconductive material. The contact pads and semiconductive material share an ohmic junction. Underbump metallurgies are formed on the contact pads. Conductive connectors are electrically coupled to the laser devices. The underbump metallurgies help prevent metal inter-diffusion between the contact pads and conductive connectors. As such, when reflowing the conductive connectors, the junction of the contact pads and semiconductive material may retain its ohmic properties.

What is claimed is: 
     
       1. A device comprising:
 a first reflective structure comprising first doped layers of a semiconductive material, alternating ones of the first doped layers being doped with a p-type dopant; 
 a second reflective structure comprising second doped layers of the semiconductive material, alternating ones of the second doped layers being doped with an n-type dopant; 
 an emitting semiconductor region disposed between the first reflective structure and the second reflective structure; 
 a contact pad on the second reflective structure, a work function of the contact pad being less than a work function of the second reflective structure; 
 a bonding layer on the contact pad, a work function of the bonding layer being greater than the work function of the second reflective structure; 
 a conductive connector on the bonding layer; 
 an interconnect structure comprising a first pad and a second pad, the conductive connector physically contacting the first pad; 
 a conductive via physically contacting the second pad; 
 an isolation material surrounding the conductive via, the first reflective structure, and the second reflective structure; 
 an electrode on and extending through the isolation material, the electrode connecting the conductive via to the first reflective structure; and 
 a first passivation layer physically contacting a sidewall of the conductive connector, the isolation material being disposed on the first passivation layer. 
 
     
     
       2. The device of  claim 1 , further comprising:
 a passivation feature on the second reflective structure and the contact pad, the bonding layer extending through the passivation feature. 
 
     
     
       3. The device of  claim 1 , wherein the semiconductive material is GaAs. 
     
     
       4. The device of  claim 3 , wherein the contact pad is a single layer of Au, GeAu, or Ni. 
     
     
       5. The device of  claim 3 , wherein the contact pad comprises:
 a first sub-layer on the second reflective structure, the first sub-layer comprising Au, GeAu, or Ni; and 
 a second sub-layer on the first sub-layer, the second sub-layer comprising a different conductive material than the first sub-layer. 
 
     
     
       6. The device of  claim 3 , wherein the bonding layer is a single layer of Ti. 
     
     
       7. The device of  claim 3 , wherein the bonding layer comprises:
 a first sub-layer on the contact pad, the first sub-layer comprising Ti; and 
 a second sub-layer on the first sub-layer, the second sub-layer comprising a different conductive material than the first sub-layer. 
 
     
     
       8. The device of  claim 1 , wherein the conductive via comprises:
 a seed layer on the second pad and sidewalls of the isolation material; and 
 a conductive material on the seed layer. 
 
     
     
       9. The device of  claim 1 , further comprising:
 a second passivation layer on and extending through the electrode and the isolation material, the second passivation layer physically contacting the first reflective structure. 
 
     
     
       10. A device comprising:
 a laser device comprising:
 a laser diode comprising an anode and a cathode; 
 a contact pad on the cathode of the laser diode; and 
 an underbump metallurgy on the contact pad; 
 
 a conductive connector connecting the underbump metallurgy of the laser device to a first pad of a substrate; 
 a first passivation layer physically contacting a sidewall of the conductive connector and a sidewall of the laser device; 
 an isolation material on the first passivation layer; 
 a conductive via extending through the isolation material and the first passivation layer, the conductive via physically contacting a second pad of the substrate; and 
 an electrode connecting the conductive via to the anode of the laser diode. 
 
     
     
       11. The device of  claim 10 , wherein an interface of the underbump metallurgy and the contact pad is free from inter-metallic compounds, the device further comprising:
 an inter-metallic compound at an interface of the underbump metallurgy and the conductive connector. 
 
     
     
       12. The device of  claim 10 , wherein the electrode has a first portion extending along a top surface of the isolation material and has a second portion extending through the isolation material to contact the anode of the laser diode. 
     
     
       13. The device of  claim 10 , wherein the contact pad comprises a first conductive material having a first work function, the underbump metallurgy comprises a second conductive material having a second work function, and the cathode comprises a semiconductive material having a third work function, the first work function less than the third work function, the second work function greater than the third work function. 
     
     
       14. The device of  claim 13 , wherein the first conductive material is Au, GeAu, or Ni; the second conductive material is Ti; and the semiconductive material is GaAs. 
     
     
       15. The device of  claim 10 , wherein the conductive via comprises:
 a conductive material; and 
 a seed layer around the conductive material, the seed layer separating the conductive material from the isolation material. 
 
     
     
       16. The device of  claim 10 , wherein the laser device further comprises:
 a passivation layer on the contact pad and the cathode of the laser diode, the underbump metallurgy extending through the passivation layer. 
 
     
     
       17. A device comprising:
 a diode comprising an anode and a cathode; 
 an electrode comprising a metal layer physically contacting the anode of the diode, the electrode and the anode sharing an ohmic junction; 
 a conductive via physically contacting the metal layer of the electrode and a first pad of an interconnect structure; 
 a contact pad physically contacting the cathode of the diode, the contact pad and the cathode sharing an ohmic junction; 
 a underbump metallurgy physically contacting the contact pad, the underbump metallurgy and the contact pad sharing a metal-metal junction; 
 a conductive connector physically contacting the underbump metallurgy and a second pad of the interconnect structure; 
 a first passivation layer physically contacting a sidewall of the conductive connector and a sidewall of the underbump metallurgy; and 
 an isolation material on the first passivation layer, the conductive via extending through the isolation material and the first passivation layer. 
 
     
     
       18. The device of  claim 17 , wherein the conductive via comprises:
 a conductive material; and 
 a seed layer between the conductive material and the isolation material. 
 
     
     
       19. The device of  claim 17 , further comprising:
 a dielectric layer on the contact pad, the underbump metallurgy extending through the dielectric layer. 
 
     
     
       20. The device of  claim 17 , further comprising:
 a second passivation layer physically contacting the isolation material, the electrode, and the anode of the diode.